The Rome Statute of the International Criminal Court entered into force in 2002 and the ICC will soon be fully operational. Earlier in the ICC process, an international conference was held in Trento to address a specific issue that is still unresolved in the post-Rome negotiations: the crime of aggression. Article 5 of the ICC Statute includes aggression, yet the Statute postpones the exercise of its jurisdiction over the crime of aggression until such time as further provisions have been prepared on the definition of this crime and on the related conditions for the Court's intervention. This important volume collects the papers given by the participants at the Trento Conference. The volume is divided into three parts: the historical background of the crime of aggression; the definition of the crime of aggression, in light of proposals in the Preparatory Commission; and various points of view on the relationship between the Court's competence in adjudicating cases of alleged crimes of aggression and the Security Council's competence.